Frequently asked questions

Answer: Unfortunately no. There are two kinds of situations in which Divider can't make groups:

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Case 1: When it is theoretically impossible to make groups because conditions for making groups are contradictory. In this case, given enough time for analysis, Divider will inform the user that it is not possible to make groups and automatically abort that process.

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Case 2: There are no visible signs that groups can't be made, but Divider is stuck for too long on step three or four of the group making process. This problems stems from the fact that there is no known algorithm that can solve this kind of problem in predictably short time (so called polynomial time) if number of groups is bigger than two. It is one of famous NP-hard problems and if somebody would find a way to solve it in polynomial time he would also become very famous and probably end up in jail because of the chaos and damage his discovery made. Apparently, nobody is that smart yet. However, that doesn't mean that it is impossible to make groups in that case. It only means that Divider is taking too much time to do that, which leads to the next frequently asked question.

Question: I left Divider to work for a whole day but it didn't finish making groups. What can I do about it?

Answer: Making less conditions usually helps. You should try to analyze the data and conclude where is the source of the problem. Here are some general guidelines:

- If Divider is stuck for too long on step 1/5, 2/5 or 5/5 there may be too many pupils, or you found a bug in the program. If there are less than 2000 pupils and Divider can't pass these steps in more than five minutes, please send us your data (e.g. export to Excel and remove pupil names) and we will try to reproduce the problem and fix the bug.

- If Divider is stuck on step 3/5 it means that there are many conditions (e.g. "To be with", "To be in", etc.) to analyze. This can happen even if number of pupils is as small as 300 if they have too many conditions. Removing some conditions and adding them back later using manual adjustment could help in this case.

- If Divider can't pass step 4/5 that means there are too many "Not to be with", "Not to be in" or "To be in" conditions. In this case removing some conditions and adding them back later using manual adjustment could be helpful, but sometimes even adding a new condition might help because it can force Divider to solve the problem in another way and that way can be quicker.

Question: Is there a way to count some pupils as more than one pupil (e.g. because they have some special educational need)?

Answer: This version of Divider doesn't support that directly. You can try to bypass that using the following idea:

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If you want to count a pupil (e.g. John) as three pupils, put his name three times in the input data (e.g. John, John1 and John2).

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For one of those pupils set "To be with" column so that it contains the other two pupils (e.g. add ordinal numbers of John1 and John2 in Johns "To be with" column).

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You might want to set their criteria values (roughly) to an average value of all pupils because you are already counting them as more than one pupil, but that is not a must.

Question: Are there any limitations regarding number of pupils, groups and group sizes?

Answer: Yes, there are. Divider should work with up to 2000 pupils, but it is tested only up to 250 because based on our experience schools typically enroll between 100 and 250 pupils per year. Number of groups should be between two and eight. If you need more than that, please write us a message and we will try to expand that limit of Divider if there are many users who need that. Group size is not limited (a group can even be empty), but if groups are larger than 64 pupils per group, manual adjustment won't be possible.

Question: I have a pupil that would like to be in group number 1 or in group number 3, but this program only allows one value in "To be in" column. Is there a way around that?

Answer: Yes, there is. Just place unacceptable groups in his "Not to be in" column, e.g. if you are making five groups place "2 4 5" (without quotation marks) in his "Not to be in" column and leave his "To be in" column empty and he will end up in group 1 or 3 after the groups are made.

Question: I have a question, but I can't find the answer here. What can I do about it?